Systems and methods for suppressing parasitic plasma and reducing within-wafer non-uniformity

ABSTRACT

A substrate processing system for depositing film on a substrate includes a processing chamber defining a reaction volume. A showerhead includes a stem portion having one end connected adjacent to an upper surface of the processing chamber. A base portion is connected to an opposite end of the stem portion and extends radially outwardly from the stem portion. The showerhead is configured to introduce at least one of process gas and purge gas into the reaction volume. A plasma generator is configured to selectively generate RF plasma in the reaction volume. An edge tuning system includes a collar and a parasitic plasma reducing element that is located around the stem portion between the collar and an upper surface of the showerhead. The parasitic plasma reducing element is configured to reduce parasitic plasma between the showerhead and the upper surface of the processing chamber.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional of U.S. application Ser. No. 14/668,174filed on Mar. 25, 2015 which claims the benefit of U.S. ProvisionalApplication No. 62/049,767, filed on Sep. 12, 2014. The entiredisclosures of the applications referenced above are incorporated hereinby reference.

FIELD

The present disclosure relates to substrate processing systems, and moreparticularly to systems and methods for suppressing parasitic plasma andreducing within-wafer non-uniformity.

BACKGROUND

The background description provided here is for the purpose of generallypresenting the context of the disclosure. Work of the presently namedinventors, to the extent it is described in this background section, aswell as aspects of the description that may not otherwise qualify asprior art at the time of filing, are neither expressly nor impliedlyadmitted as prior art against the present disclosure.

Substrate processing systems may be used to perform deposition of filmon a substrate. Substrate processing systems typically include aprocessing chamber with a reaction volume. A substrate support such as apedestal, a chuck, a plate, etc. is arranged in the processing chamber.A substrate such as a semiconductor wafer may be arranged on thesubstrate support.

In some applications, the film is deposited using plasma-enhancedchemical vapor deposition (PECVD) or plasma-enhanced atomic layerdeposition (PEALD). During PEALD, one or more PEALD cycles are performedto deposit film on the substrate. Each PEALD cycle typically includesprecursor dose, dose purge, RF plasma dose, and RF purge steps.

During deposition, process gas may be delivered to the processingchamber using a showerhead. During RF plasma dosing, RF power issupplied to the showerhead and the substrate support is grounded (orvice versa). During PEALD, plasma-enhanced conversion of the precursoroccurs on the substrate.

During the dose purge and RF purge steps, inert gas such as argon issupplied through the showerhead. In addition, a secondary purge may beperformed above the showerhead during some or all of the PEALD steps toprevent undesirable deposition in remote areas such as a backside of theshowerhead, a top plate of the processing chamber and/or walls of theprocessing chamber.

When argon is used as the secondary purge gas for some nitrogen-freeapplications such as double-patterning, parasitic plasma may occurbehind the showerhead. The power that is consumed by the parasiticplasma can be as much as 40% of the total plasma power delivered to theprocessing chamber. On-substrate delivered power loss usually results inlooser film with elevated etch rate. The parasitic plasma induced powerloss is usually non-uniform across the showerhead. More particularly,higher power loss occurs at an edge portion of the showerhead ascompared to center portions of showerhead due to the RF power suppliedat a stem portion of the showerhead.

The film deposited at the center of the substrate is denser than that atthe edge of the substrate. As a result, the film has an edge-thickprofile and high within-substrate non-uniformity, which is unfavorablefor critical dimension (CD) uniformity control in double-patterningapplications. In addition, operating the substrate processing systemwith high parasitic plasma tends to cause long term issues withwafer-to-wafer repeatability, tool drift, process defect performance,and erosion of showerhead components.

SUMMARY

A substrate processing system for depositing film on a substrateincludes a processing chamber defining a reaction volume. A showerheadincludes a stem portion having one end connected adjacent to an uppersurface of the processing chamber. A base portion is connected to anopposite end of the stem portion and extends radially outwardly from thestem portion. The showerhead is configured to introduce at least one ofprocess gas and purge gas into the reaction volume. A plasma generatoris configured to selectively generate RF plasma in the reaction volume.An edge tuning system includes a collar arranged around the stem portionof the showerhead between the base portion of the showerhead and theupper surface of the processing chamber. The collar includes one or moreholes for supplying purge gas from an inner cavity of the collar to anarea between the base portion of the showerhead and the upper surface ofthe processing chamber. The purge gas is a reactant gas. A parasiticplasma reducing element is located around the stem portion between thecollar and an upper surface of the showerhead and is configured toreduce parasitic plasma between the showerhead and the upper surface ofthe processing chamber.

In other features, the collar has a generally “T”-shaped cross-section.The one or more holes are arranged perpendicular to the stem portion ofthe showerhead. The collar includes one or more projections to provideuniform spacing between the inner cavity of the collar and an outersurface of the stem portion. The parasitic plasma reducing elementincludes a showerhead cover made of a ceramic material. The showerheadcover has a generally “C”-shaped cross section that covers the uppersurface of the showerhead and sides of the showerhead. The showerheadcover has a thickness between ⅜″ and 1″. A spacer is arranged betweenthe showerhead cover and an upper surface of the showerhead. The spacerhas a thickness between ¼″ and ½″.

In other features, the showerhead cover includes a first portion with agenerally “C”-shaped cross section that covers the upper surface of theshowerhead and sides of the showerhead and second portions that extendradially outwardly from opposite ends of the first portions in a planeparallel to the substrate. The showerhead cover has a thickness between1/16″ and ¼″. A spacer is arranged between the showerhead cover and anupper surface of the showerhead. The spacer has a thickness between ¼″and ¾″. The parasitic plasma reducing element includes a plurality ofplates that are arranged in a spaced relationship between the uppersurface of the showerhead and the collar.

In other features, the parasitic plasma reducing element furtherincludes spacers arranged between adjacent ones of the plurality ofplates. Each of the plurality of plates includes a central opening thatis larger than an outer diameter of the stem portion to allow purge gasto flow from the collar through the central opening of the plates andbetween the plates. An insert arranged between the plurality of platesand the stem portion. The insert is made of polyimide.

In other features, the insert includes a stem portion and an annularbase portion. The stem portion is arranged adjacent to and in contactwith the stem portion of the showerhead. The annular base portionextends outwardly from a showerhead-side portion of the insert.

In other features, the collar includes an inner collar arranged adjacentto the stem portion, an upper outer collar arranged around an upperportion of the inner collar, and a lower outer collar arranged around alower portion of the inner collar. The parasitic plasma reducing elementincludes a plurality of plates that are arranged in a spacedrelationship between the upper surface of the showerhead and the collar.The plurality of plates includes a central opening that is threaded. Thelower outer collar includes a threaded radially outer surface andwherein the plurality of plates is threaded onto the lower outer collar.

In other features, the inner collar includes a plurality of holes thatare aligned with a space between the upper outer collar and the lowerouter collar, and wherein purge gas flows through the plurality of holesof the inner collar. The plurality of plates includes cutouts along thecentral opening to allow purge gas flow between the plurality of plates.

In other features, the inner collar includes openings along ashowerhead-side end thereof to allow purge gas to flow between theplates and the showerhead.

In other features, the reactant gas is selected from a group includingmolecular oxygen, molecular hydrogen, molecular nitrogen, nitrous oxide,and ammonia. The reactant gas includes molecular oxygen and the filmincludes silicon dioxide. The reactant gas includes nitrous oxide andthe film includes silicon dioxide. The reactant gas includes molecularoxygen and the film includes titanium dioxide. The reactant gas includesnitrous oxide and the film includes titanium dioxide. The reactant gasincludes molecular nitrogen and the film includes silicon nitride. Thereactant gas includes ammonia and the film includes silicon nitride.

A substrate processing system for depositing film on a substrateincludes a processing chamber defining a reaction volume. A showerheadincludes a stem portion having one end connected adjacent to an uppersurface of the processing chamber. A base portion is connected to anopposite end of the stem portion and extends radially outwardly from thestem portion. The showerhead is configured to introduce at least one ofprocess gas and purge gas into the reaction volume. A plasma generatoris configured to selectively generate RF plasma in the reaction volume.An edge tuning system includes a collar arranged around the stem portionof the showerhead between the base portion of the showerhead and theupper surface of the processing chamber. The collar includes one or moreholes for supplying purge gas from an inner cavity of the collar to anarea between the base portion of the showerhead and the upper surface ofthe processing chamber. A parasitic plasma reducing element is locatedaround the stem portion between the collar and an upper surface of theshowerhead and is configured to reduce parasitic plasma between theshowerhead and the upper surface of the processing chamber. Theparasitic plasma reducing element includes a plurality of plates thatare arranged in a spaced relationship between the upper surface of theshowerhead and the collar.

Further areas of applicability of the present disclosure will becomeapparent from the detailed description, the claims and the drawings. Thedetailed description and specific examples are intended for purposes ofillustration only and are not intended to limit the scope of thedisclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

The present disclosure will become more fully understood from thedetailed description and the accompanying drawings, wherein:

FIG. 1 is a functional block diagram of an example of a substrateprocessing system with an edge tuning system to reduce parasitic plasmaaccording to the present disclosure;

FIG. 2 is a cross-sectional view of an example of a first edge tuningsystem according to the present disclosure;

FIG. 3A is an enlarged cross-sectional view of the first edge tuningsystem;

FIG. 3B is a plan view of an example of a plate;

FIGS. 4A and 4B are perspective views of an example of an inner collar;

FIG. 5 is a cross-sectional view of an example of a second edge tuningsystem according to the present disclosure;

FIG. 6 is a cross-sectional view of an example of a third edge tuningsystem according to the present disclosure; and

FIGS. 7A and 7B include a cross-sectional view and a top view,respectively, of an example of a fourth edge tuning system according tothe present disclosure; and

FIG. 8 is a graph illustrating breakdown voltage as a function ofpressure for various gases.

In the drawings, reference numbers may be reused to identify similarand/or identical elements.

DETAILED DESCRIPTION

This present disclosure relates to substrate processing systems forPECVD and PEALD with edge tuning systems to suppress parasitic plasmabehind a showerhead and to reduce within-substrate non-uniformity. Forexample in a typical PEALD process, purge gas flowing to a backside ofthe showerhead is used to reduce undesirable deposition of film at thebackside of the showerhead and other remote areas in the processingchamber. When argon is used for some applications such asdouble-patterning, the parasitic plasma ignites on a top surface of theshowerhead, which causes high within-wafer non-uniformity and a thickedge profile due to the parasitic-induced on-substrate delivered powerloss. The systems and methods described herein employ an edge tuningsystem arranged on the top surface of the showerhead to suppress theparasitic plasma and reduce within-substrate non-uniformity.

In some examples, the edge tuning system includes a combination ofcollar arranged around the stem portion and a parasitic plasma reducingelement arranged between the collar and an upper surface of theshowerhead. In some examples, the parasitic plasma reducing elementincludes a showerhead cover. In some examples, the parasitic plasmareducing element includes parallel plates.

Referring now to FIG. 1, an example of a substrate processing system 10includes a processing chamber 12 with a reaction volume. Process gasesmay be supplied to the processing chamber 12 using a showerhead 14. Insome examples, the showerhead 14 is a chandelier-type showerhead. Anedge tuning system 15 is arranged between an upper surface of theshowerhead 14 and a top surface of the processing chamber 12 to reduceparasitic plasma as will be described below. As will be describedfurther below, the edge tuning system 15 includes a collar arrangedaround the stem portion and a parasitic plasma reducing element arrangedbetween the collar and an upper surface of the showerhead.

A substrate 18 such as a semiconductor wafer may be arranged on asubstrate support 16 during processing. The substrate support 16 mayinclude a pedestal, an electrostatic chuck, a mechanical chuck or othertype of substrate support.

A gas delivery system 20 may include one or more gas sources 22-1, 22-2,. . . , and 22-N (collectively gas sources 22), where N is an integergreater than one. Valves 24-1, 24-2, . . . , and 24-N (collectivelyvalves 24), mass flow controllers 26-1, 26-2, . . . , and 26-N(collectively mass flow controllers 26), or other flow control devicesmay be used to controllably supply one or more gases to a manifold 30,which supplies a gas mixture to the processing chamber 12.

A controller 40 may be used to monitor process parameters such astemperature, pressure etc. (using one or more sensors 41) and to controlprocess timing. The controller 40 may be used to control process devicessuch as the gas delivery system 20, a substrate support heater 42,and/or an RF plasma generator 46. The controller 40 may also be used toevacuate the processing chamber 12 using a valve 50 and pump 52.

The RF plasma generator 46 generates the RF plasma in the processingchamber. The RF plasma generator 46 may be an inductive orcapacitive-type RF plasma generator. In some examples, the RF plasmagenerator 46 may include an RF supply 60 and a matching and distributionnetwork 64. While the RF plasma generator 46 is shown connected to theshowerhead 14 and the substrate support is grounded or floating, the RFplasma generator 46 can be connected to the substrate support 16 and theshowerhead 14 can be grounded or floating. In some examples, purge gas80 may be selectively supplied to the edge tuning system 15 by a valve82.

Referring now to FIGS. 2-4B, an example of a substrate processing system150 including a first edge tuning system 152 is shown. In FIGS. 2, 3Aand 3B, a showerhead 14 is shown in additional detail and includes astem portion 190 including a central cavity 192 for receiving the gasmixture from the manifold 30. The showerhead 14 further includes a baseportion 193 including a bottom or substrate-facing surface 194 and a topsurface 195. The substrate-facing surface 194 includes a plurality ofspaced holes 196. Process gas flowing through the cavity 192 of the stemportion 190 may impinge upon a dispersion plate 198 before entering acavity 199. The process gas exits the cavity 199 through the pluralityof holes 196.

The first edge tuning system 152 further includes an inner collar 212that is arranged around an outer diameter of the stem portion 190. Theinner collar 212 includes one or more holes 213 passing therethrough.The stem portion 190 passes through an inner cavity 215 of the innercollar 212. An upper outer collar 216 may have a generally “T”-shapedcross-section and is arranged above a lower outer collar 218. An upperportion 220 of the upper outer collar 216 facilitates mounting to a topsurface 222 of the processing chamber. An inner cavity 223 of the upperouter collar 216 receives the inner collar 212 and the stem portion 190of the showerhead 14. An inner cavity 227 of the lower outer collar 218also receives the inner collar 212 and the stem portion 190 of theshowerhead 14.

In some examples, a lower portion of the upper outer collar 216 maydefine a first mating surface 230 that is arranged adjacent to a secondmating surface 232 defined on an upper portion of the lower outer collar218. The plurality of holes 213 in the inner collar 212 may be alignedwith a gap 233 formed between the first and second mating surfaces 230and 232. During operation, purge gas may be supplied through the hole213 and the gap 233. A lower portion of the inner collar 212 may includeopenings 252 (FIG. 3A) to allow purge gas to flow beneath the collar212, the lower outer collar 218, and the plates 236.

A radially outer surface of the lower outer collar 218 may includethreads 234. The edge tuning system 152 further includes a parasiticplasma reducing element that includes a plurality of plates 236-1,236-2, . . . , and 236-T (collectively plates 236). The plates 236 mayinclude a threaded inner opening 237. The plates 236 may be threadedonto the threads 234 of the lower outer collar 218. The plates 236 maybe spaced with uniform or non-uniform spacing. In some examples, theplates 236 are spaced with successively increasing spacing, althoughother spacing may be used. In other examples, the plates 236 are spacedwith successively decreasing spacing, although other spacing may beused. In some examples, the plates 236 include one or more cutouts 239formed on the threaded inner opening 237. The cutouts 239 allow purgegas to flow between the plates 236.

During operation, process gas or purge gas flows through the stemportion 190 and into the cavity 199. The process gas or purge gas isdistributed across the substrate 18 by the plurality of holes 196.Secondary purge gas is supplied between the inner collar 212 and thestem portion 190. The purge gas flows through the holes 213 and into thegap 233. The purge gas also flows through the openings 252 and thecutouts 239 between the plates 236. The edge tuning system 152 helps toreduce parasitic plasma during steps that include the use of plasma.

In some examples, the plates 236 are made of aluminum, although othermaterials may be used. In some examples, the plates 236 are made ofAl7075 aluminum, although other materials may be used. In some examples,the plates 236 have a thickness of 0.070″ to 0.110″. In some examples,the plates 236 have a thickness of 0.090″. In some examples, a top oneof the plates 236 has nine of the cutouts 239 (each at 0.125″) that arespaced around the inner opening 237 and plates arranged below the topone of the plates have fifteen cutouts 239 (each at 0.125″) that arespaced around the inner opening 237, although additional or fewercutouts may be used. The cutouts 239 may be spaced in a uniform ornon-uniform pattern.

In FIGS. 4A and 4B, the inner collar 212 is shown in further detail. Theinner collar 212 is generally cylindrical and includes the inner cavity215 and first and second openings 260 and 261 at opposite ends thereof.An inner surface 264 of the inner collar 212 may include one or moreprojections 280 that project radially inwardly and may extend the lengthof the inner collar 212 or part of the length of the inner collar 212.The one or more projections 280 maintain a predetermined spacing betweenthe inner collar 212 and a radially outer surface of the stem portion190 of the showerhead 14.

The inner collar 212 in FIGS. 4A and 4B includes the holes 213 thatextend from the inner surface 264 to an outer surface 282 of the innercollar 212. A notch 290 may be formed in the radially outer surface 282of the inner collar 212 adjacent to an upper portion of the inner collar212. The openings 252 may be defined by one or more scalloped or arcuatesections 262. For example, in FIG. 4, there are four scalloped orarcuate sections 262-1, 262-2, 262-3 and 262-4. In some examples, ajunction 263 between arcuate sections 262-1 and 262-2 is located lowerthan other junctions between other ones of the arcuate sections 262. Theinner collar 212 may rest on the junction 263.

Referring now to FIG. 5, an example of a substrate processing system 300including a second edge tuning system 306 is shown. The second edgetuning system 306 includes a collar 308 arranged around the stem portion190 and a parasitic plasma reducing element that includes a showerheadcover 320 arranged around the base portion 193 of the showerhead 14.

The collar 308 may include an upper “T”-shaped section similar to thatshown in FIG. 2 to attach the collar 308 and the showerhead 14 to theupper surface of the processing chamber. The collar 308 includes acentral cavity 309 that receives the stem portion 190 of the showerhead14. The collar 308 further includes a plurality of holes 314 that extendthrough the collar 308. In some examples, the plurality of holes 314 isarranged perpendicular to the stem portion 190. During operation, purgegas flows through the plurality of holes 314 and below a lower portionof the collar 308 to purge areas between the showerhead cover 320, theshowerhead 14 and the upper surface of the processing chamber.

The showerhead cover 320 has a generally “C”-shaped cross-section andincludes an upper surface 322, a lower surface 324 and a central opening326 for receiving the stem portion 190. The central opening 326 mayprovide additional clearance between the stem portion 190 to allow purgegas flow between the showerhead 14 and the showerhead cover 320. Radialend portions 330 of the showerhead cover 320 extend past a radiallyouter edge of the base portion 193 of the showerhead 14 and thendownwardly. A lower portion 332 of the showerhead cover 320 may extendto the lower surface 194 of the base portion 193 of the showerhead 14 orslightly above or below the lower surface 194 of the base portion 193 ofthe showerhead 14. One or more spacers 338 may be provided to maintainspacing between the showerhead cover 320 and the showerhead 14. In someexamples, the showerhead cover 320 is made of ceramic, although othermaterials may be used.

In some examples, the showerhead cover 320 has a thickness between ⅜″and 1″. In some examples, a radially outer end of the showerhead 14 isspaced 0.120″ from an inner surface of the showerhead cover 320. In someexamples, the spacer 338 has a thickness of ¼″ to ½″. In some examples,the spacer 338 has a thickness of ⅜″.

Referring now to FIG. 6, an example of a substrate processing system 400including a third edge tuning system 406 is shown. The third edge tuningsystem 406 includes the collar 308 described above and a parasiticplasma reducing element that includes a showerhead cover 420. Theshowerhead cover 420 includes a first portion including a generally“C”-shaped cross-section and includes an upper surface 422, a lowersurface 424 and a central opening 426 for receiving the stem portion190. Radially outer end portions 430 of the showerhead cover 420 extendover a radially outer edge of the base portion 193 of the showerhead 14.A lower portion 432 of the showerhead cover 420 may extend to the lowersurface 194 of the base portion 193 of the showerhead 14 or slightlyabove or below the lower surface 194 of the base portion 193 of theshowerhead 14 before extending radially outwardly in a plane generallyparallel to the substrate 18 as shown at 433. One or more spacers 438may be provided to maintain spacing between the showerhead cover 420 andthe showerhead 14.

In some examples, the showerhead cover 420 has a thickness between 1/16″and ¼″. In some examples, a radially outer end of the showerhead 14 isspaced (e.g. 0.03125″) from an inner surface 450 of the showerhead cover420 and a surface 452 is spaced (e.g. 0.03125″) above the bottom surface194 of the showerhead 14. In some examples, the spacer 438 has athickness between ¼″ and ¾″. In some examples, the spacer 438 has athickness of ½″.

Referring now to FIGS. 7A and 7B, an example of a substrate processingsystem 500 including a fourth edge tuning system 506 is shown. Thefourth edge tuning system 506 includes the collar 308 described aboveand a parasitic plasma reducing element that includes a plurality ofplates 514-1, 514-2, . . . , and 514-R (collectively plates 514). Theplates 514 may be spaced apart using spacers 516 or other mechanism.

In some examples, the spacers 516 may be made of ceramic. In someexamples, the plates 514 are made of aluminum such as Al7075 aluminum,although other materials may be used. In some examples, the plates 514have a thickness of 0.070″ to 0.110″. In some examples, the plates 514have a thickness of 0.090″.

An insert 530 may be arranged between the stem portion 190 of theshowerhead 14 and radially inner edges of the plates 514 and the cavity309 of the collar 308. In some examples, the insert 530 is made ofplastic such as polyimide-based plastic (such as Vespel®), althoughother materials may be used. In some examples, the insert 530 mayinclude an annular body portion 532 and a stem portion 534. The annularbody portion 532 extends radially outwardly from a lower portion of thestem portion 534. In FIG. 7B, the plates 514 are shown to include anopening 515 that is larger than the stem portion 190. As a result, purgegas flows between the plates 514.

In some examples, the systems and methods described herein performsecondary purging with a reactant gas instead of non-reactive or inertgases. For example only, molecular oxygen (O₂) or nitrous oxide (N₂O)may be used for the secondary purging when depositing silicon dioxide(SiO₂) or titanium dioxide (TiO₂) films. For example only, molecularnitrogen (N₂) or ammonia (NH₃) may be used for secondary purging whendepositing silicon nitride (SiN) films. Additionally while SiO₂ and TiO₂are specifically disclosed herein, the present disclosure relates toother ALD oxide or nitride films including silicon (Si), hafnium (Hf),aluminum (Al), titanium (Ti), zirconium (Zr), etc.

In some examples, molecular oxygen or molecular hydrogen are used as asecondary purge gas. The use of reactant gas such as molecular oxygenhelps to prevent light-up and/or associated hollow cathode discharge(HCD) signatures that are observed when argon is used. Argon has a lowerbreakdown voltage than molecular oxygen at typical process pressures.When a reactant gas such as molecular oxygen is used instead of argon,thickness variations on the front side edge profile are also eliminated(particularly at a notch).

Referring now to FIG. 8, a Paschen curve is shown. The breakdown voltageof inert gases such as Argon is relatively low at typical processpressures such as 2-10 Torr. As can be seen, the breakdown voltage ofmolecular hydrogen and molecular nitrogen are higher for some processpressures. In some examples, the secondary purge gas is selected to havea higher breakdown voltage than argon at the selected process pressure.For example only, molecular hydrogen may be used when the processingchamber operates at process pressures from 2-3 Torr but may not be usedat higher process pressures where argon has a higher breakdown voltage.

In other features, the film is deposited using atomic layer deposition.The method further includes maintaining the processing chamber at avacuum pressure of 2 to 3 Torr.

The foregoing description is merely illustrative in nature and is in noway intended to limit the disclosure, its application, or uses. Thebroad teachings of the disclosure can be implemented in a variety offorms. Therefore, while this disclosure includes particular examples,the true scope of the disclosure should not be so limited since othermodifications will become apparent upon a study of the drawings, thespecification, and the following claims. As used herein, the phrase atleast one of A, B, and C should be construed to mean a logical (A OR BOR C), using a non-exclusive logical OR, and should not be construed tomean “at least one of A, at least one of B, and at least one of C.” Itshould be understood that one or more steps within a method may beexecuted in different order (or concurrently) without altering theprinciples of the present disclosure.

In some implementations, a controller is part of a system, which may bepart of the above-described examples. Such systems can comprisesemiconductor processing equipment, including a processing tool ortools, chamber or chambers, a platform or platforms for processing,and/or specific processing components (a wafer substrate support, a gasflow system, etc.). These systems may be integrated with electronics forcontrolling their operation before, during, and after processing of asemiconductor wafer or substrate. The electronics may be referred to asthe “controller,” which may control various components or subparts ofthe system or systems. The controller, depending on the processingrequirements and/or the type of system, may be programmed to control anyof the processes disclosed herein, including the delivery of processinggases, temperature settings (e.g., heating and/or cooling), pressuresettings, vacuum settings, power settings, radio frequency (RF)generator settings, RF matching circuit settings, frequency settings,flow rate settings, fluid delivery settings, positional and operationsettings, wafer transfers into and out of a tool and other transfertools and/or load locks connected to or interfaced with a specificsystem.

Broadly speaking, the controller may be defined as electronics havingvarious integrated circuits, logic, memory, and/or software that receiveinstructions, issue instructions, control operation, enable cleaningoperations, enable endpoint measurements, and the like. The integratedcircuits may include chips in the form of firmware that store programinstructions, digital signal processors (DSPs), chips defined asapplication specific integrated circuits (ASICs), and/or one or moremicroprocessors, or microcontrollers that execute program instructions(e.g., software). Program instructions may be instructions communicatedto the controller in the form of various individual settings (or programfiles), defining operational parameters for carrying out a particularprocess on or for a semiconductor wafer or to a system. The operationalparameters may, in some embodiments, be part of a recipe defined byprocess engineers to accomplish one or more processing steps during thefabrication of one or more layers, materials, metals, oxides, silicon,silicon dioxide, surfaces, circuits, and/or dies of a wafer.

The controller, in some implementations, may be a part of or coupled toa computer that is integrated with the system, coupled to the system,otherwise networked to the system, or a combination thereof. Forexample, the controller may be in the “cloud” or all or a part of a fabhost computer system, which can allow for remote access of the waferprocessing. The computer may enable remote access to the system tomonitor current progress of fabrication operations, examine a history ofpast fabrication operations, examine trends or performance metrics froma plurality of fabrication operations, to change parameters of currentprocessing, to set processing steps to follow a current processing, orto start a new process. In some examples, a remote computer (e.g. aserver) can provide process recipes to a system over a network, whichmay include a local network or the Internet. The remote computer mayinclude a user interface that enables entry or programming of parametersand/or settings, which are then communicated to the system from theremote computer. In some examples, the controller receives instructionsin the form of data, which specify parameters for each of the processingsteps to be performed during one or more operations. It should beunderstood that the parameters may be specific to the type of process tobe performed and the type of tool that the controller is configured tointerface with or control. Thus as described above, the controller maybe distributed, such as by comprising one or more discrete controllersthat are networked together and working towards a common purpose, suchas the processes and controls described herein. An example of adistributed controller for such purposes would be one or more integratedcircuits on a chamber in communication with one or more integratedcircuits located remotely (such as at the platform level or as part of aremote computer) that combine to control a process on the chamber.

Without limitation, example systems may include a plasma etch chamber ormodule, a deposition chamber or module, a spin-rinse chamber or module,a metal plating chamber or module, a clean chamber or module, a beveledge etch chamber or module, a physical vapor deposition (PVD) chamberor module, a chemical vapor deposition (CVD) chamber or module, anatomic layer deposition (ALD) chamber or module, an atomic layer etch(ALE) chamber or module, an ion implantation chamber or module, a trackchamber or module, and any other semiconductor processing systems thatmay be associated or used in the fabrication and/or manufacturing ofsemiconductor wafers.

As noted above, depending on the process step or steps to be performedby the tool, the controller might communicate with one or more of othertool circuits or modules, other tool components, cluster tools, othertool interfaces, adjacent tools, neighboring tools, tools locatedthroughout a factory, a main computer, another controller, or tools usedin material transport that bring containers of wafers to and from toollocations and/or load ports in a semiconductor manufacturing factory.

What is claimed is:
 1. A substrate processing system for depositing filmon a substrate, comprising: a processing chamber defining a reactionvolume; a showerhead including: a stem portion having one end connectedadjacent to an upper surface of the processing chamber; and a baseportion connected to an opposite end of the stem portion and extendingradially outwardly from the stem portion, wherein the showerhead isconfigured to introduce at least one of process gas and purge gas intothe reaction volume; a plasma generator configured to selectivelygenerate RF plasma in the reaction volume; and an edge tuning systemincluding: a collar arranged around the stem portion of the showerheadbetween the base portion of the showerhead and the upper surface of theprocessing chamber, wherein the collar includes one or more holes forsupplying purge gas from an inner cavity of the collar to an areabetween the base portion of the showerhead and the upper surface of theprocessing chamber; and a parasitic plasma reducing element including ashowerhead cover that is made of a ceramic material and that includes: afirst portion with a “C”-shaped cross section that covers an uppersurface of the showerhead and sides of the showerhead; and a secondportion that extends radially outwardly from opposite ends of the firstportion in a plane that is parallel to the substrate.
 2. The substrateprocessing system of claim 1, wherein the showerhead cover has athickness between ⅜″ and 1″.
 3. The substrate processing system of claim2, further comprising a spacer arranged between the showerhead cover andthe upper surface of the showerhead.
 4. The substrate processing systemof claim 3, wherein the spacer has a thickness between ¼″ and ½″.
 5. Thesubstrate processing system of claim 1, wherein the showerhead cover hasa thickness between 1/16″ and ¼″.
 6. The substrate processing system ofclaim 5, further comprising a spacer arranged between the showerheadcover and the upper surface of the showerhead.
 7. The substrateprocessing system of claim 6, wherein the spacer has a thickness between¼″ and ¾″.
 8. The substrate processing system of claim 1, wherein theone or more holes of the collar are configured to supply purge gas fromthe inner cavity of the collar to an area between the upper surface ofthe processing chamber and an upper surface of the parasitic plasmareducing element.
 9. The substrate processing system of claim 1, whereina radially outer end of the base portion of the showerhead is spaced0.120″ radially inwardly from an inner surface of the second portion ofthe parasitic plasma reducing element.
 10. The substrate processingsystem of claim 1, wherein the first portion of the parasitic plasmareducing element includes: a third portion that extends radiallyoutwardly from the stem portion of the showerhead in a direction that isperpendicular to the stem portion of the showerhead; and a fourthportion that extends perpendicularly to the third portion away from theupper surface of the processing chamber, wherein the fourth portion isradially outward from a radially outer edge of the base portion of theshowerhead.
 11. The substrate processing system of claim 10, wherein thesecond portion extends radially outwardly from the fourth portion in aplane that is parallel to the substrate.
 12. The substrate processingsystem of claim 10, wherein the extension of the fourth portion awayfrom the upper surface of the processing chamber terminates at a pointon a plane that is between an upper surface and a lower surface of thebase portion of the showerhead.
 13. The substrate processing system ofclaim 10, wherein the extension of the fourth portion away from theupper surface of the processing chamber terminates at a point on a planethat is between a lower surface of the base portion of the showerheadand the substrate.
 14. The substrate processing system of claim 10,wherein the extension of the fourth portion away from the upper surfaceof the processing chamber terminates at a point on a plane of a lowersurface of the base portion of the showerhead.
 15. The substrateprocessing system of claim 1, wherein the collar does not include anyholes that are configured to supply purge gas from the inner cavity ofthe collar to an area between a lower surface of the showerhead coverand an upper surface of the base portion of the showerhead.
 16. Thesubstrate processing system of claim 1, wherein the base portion of theshowerhead includes a plurality of holes configured to introduce the atleast one process gas and purge gas into the reaction volume.
 17. Thesubstrate processing system of claim 16 wherein the stem portion of theshowerhead includes a central cavity through which the at least oneprocess gas and purge gas flow to the plurality of holes of the baseportion.
 18. The substrate processing system of claim 17, wherein theshowerhead further includes a distribution plate configured todistribute the at least one process gas and purge gas from the centralcavity to the plurality of holes of the base portion.
 19. The substrateprocessing system of claim 17, wherein the inner cavity of the collar islocated radially outwardly from the central cavity of the stem portion.20. The substrate processing system of claim 1, wherein the collarincludes at least three holes for supplying purge gas from the innercavity of the collar to the area between the base portion of theshowerhead and the upper surface of the processing chamber.